## Answers

#### Explanation:

The formula for distance of two Points is given by

so we get

squaring we get

combining like Terms

using the quadratic formula we get

so

#### Explanation:

#"to calculate the distance d use the "color(blue)"distance formula"#

#•color(white)(x)d=sqrt((x_2-x_1)^2+(y_2-y_1)^2)#

#"let "(x_1,y_1)=(3,1)" and "(x_2,y_2)=(-5,a)#

#d=sqrt((-5-3)^2+(a-1)^2)=sqrt89#

#sqrt(64+(a-1)^2)=sqrt89#

#color(blue)"square both sides"#

#64+(a-1)^2=89#

#"subtract 64 from both sides"#

#(a-1)^2=25#

#color(blue)"take the square root of both sides"#

#sqrt((a-1)^2)=+-sqrt25larrcolor(blue)"note plus or minus"#

#a-1=+-5#

#"add 1 to both sides"#

#a=1+-5#

#a=1-5=-4" or "a=1+5=6#